1. Field of the Invention
This invention is in the field of leaching or lixivating metal from metal bearing solid matter involving treatment first in a vibratory grinding mill and then in a vibratory reactor where the precipitation of metal values takes place.
2. Description of the Prior Art
There is a method for leaching and precipitating metal from metal bearing solid matter described in German AS 26 02 849 in which the leaching process as well as a precipitation is carried out simultaneously in a vibrating reaction vessel. From this known method, it might be advisable to carry out the leaching and precipitation simultaneously with the mechanical crushing of the metal bearing solid matter.
Attempts to simultaneously leach and precipitate copper ores of different origin with diluted sulfuric acid in a vibratory reactor have shown that the dissolution of the sufuric acid soluble components of the charged material proceeds significantly slower than the cementation of the copper ions disposed in the solution, and thus determines the speed with which the combined method can be carried out. In order to achieve a satisfactory yield in the case of this method, reaction times on the average of about 300 seconds or so had to be used whereas only about 60 seconds were required for the cementation. This long reaction time for leaching, in relation to cementation, would lead to an unrealistically large number of oscillating reactors being necessary for the use of such a system in a medium size plant.
In order to shorten the leaching time in the vibrating reactor and thereby reduce the number of vibrating reactors required, the simultaneous leaching and precipitation could be carried out such that a preleaching of conventional type would be effected outside the vibrating reactor, for example, in a stirring receptacle. Subsequently, the pulp thus produced could be subjected to a treatment in the vibrating reactor whereby the pulverization, post-leaching and cementation simultaneously take place in the vibrating reactor. In this modified method of operation, there is the disadvantage that because of the brief dwell time of direct contact in the vibrating reactor, there is an unsatisfactory grinding resulting in unfavorable precipitation, thereby reducing the yield of the desired metal.
Experimental results with this modified method of operation did, indeed, lead to the finding that the leaching time in the vibrating reactor could be shortened to 120 seconds, with a preceding stirring or agitation leaching of approximately 3600 seconds in order to achieve a similar yield of the sulfuric acid soluble component as was possible in the vibration grinding mill without preleaching. Accordingly, in this modified method, there resulted only an exchange of vibrating reactors for a corresponding number of stirring or agitating receptacles, without any improvement in result.
In the case of the known methods, diluted sulfuric acid attacks metallic reactor materials to a considerable extent. This causes a considerable wear or requires a lining of the reactor walls with a rubber or ceramic material. This is a substantial capital expenditure, and substantially increases the expense.